Triploblasts and Annelids

These flashcards cover key vocabulary and concepts related to triploblasts, embryonic development, and the classification of annelids.

Triploblasts

Organisms having three primary germ layers: ectoderm, mesoderm, and endoderm.

Gastrulation

The process during early embryonic development that rearranges the embryo into a triploblastic gastrula.

Protostomes

Organisms in which the blastopore develops into the mouth; includes mollusks, annelids, and arthropods.

Deuterostomes

Organisms in which the blastopore develops into the anus; includes echinoderms and chordates.

Blastopore

The opening that develops during gastrulation; in protostomes it becomes the mouth, and in deuterostomes it becomes the anus.

Mesoderm

The middle layer of germ tissue in triploblastic organisms that develops into muscle, bone, and other internal organs.

Archenteron

The primitive gut formed during the early stages of embryonic development.

Diploblasty

Organisms with two primary germ layers: ectoderm and endoderm.

Cnidaria

A phylum of primarily aquatic animals that are diploblastic and have radial symmetry.

Coelom

The body cavity that is lined by mesoderm; a significant feature of triploblastic organisms.

Acoelomate

Organisms that lack a body cavity, having solid mesoderm tissue.

Pseudocoelomate

Organisms with a body cavity that is not fully lined by mesoderm.

Nematoda

A phylum that includes roundworms; known for their pseudocoelomate body structure.

Annelida

A phylum of segmented worms that typically have a true coelom, including earthworms and leeches.

Metamerism

The segmentation of the body into repetitive segments, characteristic of annelids.

Dioecious

Organisms that have distinct male and female individuals for reproduction.

Hermaphroditic

Organisms that possess both male and female reproductive organs.

Protonephridia

The excretory structures found in many flatworms which are involved in osmoregulation.

Closed circulatory system

A system where the blood circulates within vessels and is separate from the coelomic fluid.

Ganglia

Clusters of nerve cell bodies that function as a central nervous system.